Does N70 read xxx.jar format ebook ??

.jar files are "Java ARchive" files, which are actually .zip files with the .jar extension, instead.

Now, the .jar file can contain anything, and in this case it is hard to guess what an ".jar format ebook" is, because there are probably tens of different ebook file formats that could be contained in a .jar file (i.e., there is no actual .jar format ebook, but your .jar file contains an ebook file in some format).

It might also be useful to know if the .jar file also contains an ebook reader application, or just the book data.

If just the ebook data, then you must have an ebook reader app on your phone, and knowing what it is might be useful (it could work on an N70, but it is hard to say without knowing what application you really have).